IntroductionThis post is for Day 21 of the [Merpay & Mercoin Advent Calendar 2025](https://engineering.mercari.com/blog/

Mercari's platform is a resource for developers and technology enthusiasts, offering insights into engineering challenges, technology stack, and culture at Mercari. Through articles, tech talks, and open-source contributions, Mercari offers insights into building innovative and scalable technology solutions. Developers can learn about Mercari's engineering culture, agile methodologies, and contributions to the broader tech community.

Mercari Engineering

Mercari Group implemented a company-wide DevEx improvement initiative over nine months, evolving from team-level efforts with mixed results to a dual-layer approach combining bottom-up team improvements with top-down organizational policies. The breakthrough came in Phase 2 when VPoE-led initiatives focused on Deep Work achieved 16% improvement in a single quarter by establishing clear policies like no-meeting time blocks and meeting consolidation. Success required three key roles (Executive Sponsor, Champion, Manager), proper structure with 6-12 month timebases, and connecting developer pain to business outcomes. Ongoing challenges include horizontal deployment across diverse organizations, measuring long-term business impact, and maintaining momentum across multiple quarters.

Nine Months of DevEx Improvement at Mercari Group

Scaling Improvements: From Teams to Organization-Wide